Touch panel and driving method of touch panel

ABSTRACT

A touch panel including a first substrate, a second substrate, a first conductive layer, a second conductive layer, a third conductive layer, and a number of spacers is provided. The first substrate has an upper surface and a bottom surface opposite to the upper surface. The second substrate is parallel to the first substrate. The first conductive layer is disposed on the upper surface of the first substrate, while the second conductive layer is disposed on the bottom surface of the first substrate. The third conductive layer is disposed on the second substrate and interposed between the second substrate and the second conductive layer. The spacers are interposed between the second conductive layer and the third conductive layer. The touch panel has functions of multi-touch, contact-touch and non-contact touch, and the touch panel can be operated by conductive objects or dielectric objects.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 97106063, filed on Feb. 21, 2008. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a touch panel and a driving methodthereof. More particularly, the present invention relates to a touchpanel and a driving method thereof, wherein the touch panel is equippedwith functions of contact-touch, non-contact touch, and multi-touch andcan be operated via objects made of conductive materials or dielectricmaterials.

2. Description of Related Art

Information technologies (ITs), wireless mobile communications, andinformation home appliances have been rapidly developed and widelyapplied. To meet current demands on portable, compact, and user-friendlyIT products, touch panels have been introduced as input interfaces inreplacement of conventional keyboards or mice.

At this current stage, the touch panels can be categorized into aresistive touch panel and a capacitive touch panel based on theirdriving manner and structural design. To operate a resistive touchpanel, a user should press the resistive touch panel, such that parts ofareas within the resistive touch panel are electrically conducted andthereby coordinate signals indicative of coordinates of touch points areproduced. This type of touch panel exhibits a disadvantage of lowdurability. Moreover, the resistive touch panel can only sense asingle-touch input, while the resistive touch panel is not able torecognize multi-touch gestures. Hence, consumers' demands on diversefunctions of the products cannot be satisfied.

On the contrary, the capacitive touch panel has a multiple touch sensingfeature and thus has become more and more popular. In addition, nodirect touch contact is required by operating the capacitive touchpanel, and therefore the capacitive touch panel is relatively durable incomparison with the resistive touch panel. Moreover, the capacitivetouch panel which can be operated in a non-contact manner can be placedwithin housings of the IT products, so as to look after the consumers'requirements for fantastic exterior designs of the IT products. However,notwithstanding the easy operation, the capacitive touch panel cannot beoperated by the users wearing gloves or by means of insulatingmaterials. As such, said two types of the touch panels are barelysatisfactory so far and further improvement is deemed necessary.

SUMMARY OF THE INVENTION

The present invention is directed to a touch panel for resolving anissue regarding an inconvenient operation of a conventional touch panel.

The present invention is further directed to a driving method of a touchpanel, wherein the driving method enables the touch panel to be operatedin a more flexible manner.

The present invention provides a touch panel including a firstsubstrate, a second substrate, a first conductive layer, a secondconductive layer, a third conductive layer, and a plurality of spacers.The first substrate has an upper surface and a bottom surface oppositeto the upper surface, and the second substrate is parallel to the firstsubstrate. The first conductive layer is disposed on the upper surfaceof the first substrate, while the second conductive layer is disposed onthe bottom surface of the first substrate. Besides, the third conductivelayer is disposed on the second substrate and interposed between thesecond substrate and the second conductive layer. The spacers areinterposed between the second conductive layer and the third conductivelayer.

According to an embodiment of the present invention, the touch panelfurther includes a plurality of linear electrodes disposed on the secondsubstrate and positioned around the third conductive layer. In addition,a material of the linear electrodes includes metals. Practically, thematerial of the linear electrodes is, for example, gold, silver, copper,aluminum, or a combination thereof.

According to an embodiment of the present invention, the first substrateis a flexible substrate.

According to an embodiment of the present invention, the secondsubstrate includes a flexible substrate or a rigid substrate.

According to an embodiment of the present invention, the firstconductive layer includes a plurality of bar-shaped conductive patternssubstantially arranged in parallel. The second conductive layer alsoincludes, for example, a plurality of bar-shaped conductive patternssubstantially arranged in parallel. Here, a long axis of the bar-shapedconductive patterns of the second conductive layer is substantiallyperpendicular to a long axis of the bar-shaped conductive patterns ofthe first conductive layer.

According to an embodiment of the present invention, a material of thefirst conductive layer, the second conductive layer, and the thirdconductive layer includes an oxide conductive material, such as indiumtin oxide (ITO) or indium zinc oxide (IZO).

According to an embodiment of the present invention, the touch panelfurther includes a planar layer that covers the first substrate.

According to an embodiment of the present invention, the firstsubstrate, the second substrate, the first conductive layer, the secondconductive layer, and the third conductive layer are all made oftransparent materials.

The present invention further provides a driving method of a touchpanel. The driving method is suitable for driving the touch paneldescribed in the above-identified embodiments. In the driving method, acoordinate signal is outputted based on a voltage variation of thesecond conductive layer or based on a variation of an inducedcapacitance between the first conductive layer and the second conductivelayer.

According to an embodiment of the present invention, the driving methodof the touch panel further includes inputting a reference signal to thethird conductive layer.

According to an embodiment of the present invention, the driving methodof the touch panel further includes detecting the variation of theinduced capacitance between the first conductive layer and the secondconductive layer.

According to an embodiment of the present invention, the driving methodof the touch panel further includes detecting the voltage variation ofthe second conductive layer.

The resistive touch panel structure and the capacitive touch panelstructure are integrated on two substrates according to the presentinvention, and thus the touch panel of the present invention ischaracterized by advantages of both the resistive touch panel and thecapacitive touch panel. In particular, the touch panel of the presentinvention is equipped with functions of contact-touch, non-contacttouch, and multi-touch.

To make the above and other objectives, features, and advantages of thepresent invention more comprehensible, several embodiments accompaniedwith figures are detailed as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a touch panel according to anembodiment of the present invention.

FIG. 2 is a flowchart of a driving method of a touch panel according toan embodiment of the present invention.

FIG. 3A is a schematic top view of a first conductive layer of the touchpanel depicted in FIG. 1 according to the present invention.

FIG. 3B is a schematic top view of a second conductive layer of thetouch panel depicted in FIG. 1 according to the present invention.

FIG. 3C is a schematic top view of a third conductive layer of the touchpanel depicted in FIG. 1 according to the present invention.

DESCRIPTION OF EMBODIMENTS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a cross-sectional view of a touch panel according to anembodiment of the present invention. Referring to FIG. 1, a touch panel100 includes a first substrate 110, a second substrate 120, a firstconductive layer 130, a second conductive layer 140, a third conductivelayer 150, and a plurality of spacers 160. The first substrate 110 hasan upper surface 112 and a bottom surface 114 opposite to the uppersurface 112, and the second substrate 120 is parallel to the firstsubstrate 110. The first conductive layer 130 is disposed on the uppersurface 112 of the first substrate 110, while the second conductivelayer 140 is disposed on the bottom surface 114 of the first substrate110. Besides, the third conductive layer 150 is disposed on the secondsubstrate 120 and interposed between the second substrate 120 and thesecond conductive layer 140. The spacers 160 are interposed between thesecond conductive layer 140 and the third conductive layer 150. Inaddition, a plurality of linear electrodes 170 is further disposed onthe second substrate 120.

A material of the first conductive layer 130, the second conductivelayer 140, and the third conductive layer 150 is, for example, an oxideconductive material. Currently, some of the common oxide conductivematerials include ITO, IZO, and so forth. In general, said oxideconductive materials are transparent, and thus a touch area defined bythe first conductive layer 130, the second conductive layer 140, and thethird conductive layer 150 in the touch panel 100 is also transparent.Here, the touch panel 100 can be attached to a display panel to form atouch display panel having a touch control feature and an image displayfunction. In order to protect the touch panel 100 and prevent the firstconductive layer 130 from being contaminated, a planar layer 180 can bedisposed to cover the first conductive layer 130. In addition, the firstsubstrate 110 is made of a flexible material, for example. Namely, thefirst substrate 110 can be a flexible substrate. On the other hand, thesecond substrate 120 can be either a flexible substrate or a rigidsubstrate. The rigid substrate is, for example, a glass substrate or asubstrate made of other rigid materials, while the flexible substrateis, for example, made of a plastic material or other flexible materials.Besides, the planar layer 180 can also be made of flexible dielectricmaterials.

The first substrate 110, the first conductive layer 130, and the secondconductive layer 140 can together form a capacitive touch panel having asingle substrate structure, while the first substrate 110, the secondsubstrate 120, the second conductive layer 140, the third conductivelayer 150, and the plurality of spacers 160 can together form aresistive touch panel. The first substrate 110 made of the dielectricmaterial maintains an appropriate space between the first conductivelayer 130 and the second conductive layer 140. A capacitive structurecan be formed between the first conductive layer 130 and the secondconductive layer 140 in the capacitive touch panel. When a conductivematerial approaches the first conductive layer 130, an inducedcapacitance is generated between the first conductive layer 130 and thesecond conductive layer 140 at a position corresponding to theapproaching conductive material. On the other hand, in the resistivetouch panel, as a pressure is pointedly applied to the first substrate110, the flexibility of the first substrate 110 is conducive toelectrically conducting between the second conductive layer 140 and thethird conductive layer 150. At this time, a corresponding voltage isgenerated as a sensing signal by the second conductive layer 140 at aposition where the pressure is applied to the first substrate 110.

FIG. 2 is a flowchart of a driving method of a touch panel according toan embodiment of the present invention. Referring to FIGS. 1 and 2, thedriving method is suitable for driving the touch panel 100 illustratedin FIG. 1. In step 210 of the driving method, a variation of an inducedcapacitance between the first conductive layer 130 and the secondconductive layer 140 is detected. In step 220A, a voltage variation ofthe second conductive layer 140 is detected. Accordingly, a coordinatesignal is outputted based on the variation of the induced capacitance orthe voltage variation (step 230). In practice, the driving methodfurther includes inputting a reference signal to the third conductivelayer 150 before the voltage variation of the second conductive layer140 is detected (step 220B).

Specifically, the driving method of the touch panel 100 in the presentembodiment includes performing step 210, for example. That is to say,the variation of the induced capacitance between the first conductivelayer 130 and the second conductive layer 140 is detected. If thereexists the variation of the induced capacitance between the firstconductive layer 130 and the second conductive layer 140, step 230 canbe performed, so as to generate a corresponding coordinate signal basedon the variation of the induced capacitance. On the other hand, if novariation of the induced capacitance between the first conductive layer130 and the second conductive layer 140 occurs, a reference signal isthen inputted to the third conductive layer 150 (step 220B), and step220A is performed to detect the voltage variation of the secondconductive layer 140. Here, the voltage variation can be converted tothe corresponding coordinate signal (step 230).

When the reference signal is inputted to the third conductive layer 150,step 220A in the driving method of the present embodiment can also beimplemented to detect the voltage variation of the second conductivelayer 140. If there exists the voltage variation of the secondconductive layer 140, the voltage variation is converted to thecoordinate signal (step 230). By contrast, if there is no voltagevariation of the second conductive layer 140, step 210 is carried out toconvert the variation of the induced capacitance between the firstconductive layer 130 and the second conductive layer 140 to thecoordinate signal (step 230). Namely, it is not limited in the presentinvention to first detect the variation of the induced capacitancebetween the first conductive layer 130 and the second conductive layer140 or to first detect the voltage variation of the second conductivelayer 140. When only one of the electrical parameters is detected andobtained, the corresponding coordinate signal can then be produced. Inother words, a control circuit can drive the touch panel 100 merely byhaving one of the two parameters varied.

FIGS. 3A through 3C are schematic top views respectively illustratingthe first conductive layer, the second conductive layer, and the thirdconductive layer of the touch panel depicted in FIG. 1 according to thepresent invention. Referring to FIGS. 3A and 3B, the first conductivelayer 130 and the second conductive layer 140 are composed of aplurality of bar-shaped conductive patterns X1˜X4 and Y1˜Y4,respectively. The bar-shaped conductive patterns X1˜X4 are approximatelyin parallel, and so are the bar-shaped conductive patterns Y1˜Y4. Anextending direction of the bar-shaped conductive patterns X1˜X4intersects an extending direction of the bar-shaped conductive patternsY1˜Y4, whereas practically the said two extending directions can also beperpendicular to each other. Parts of the regions occupied by thebar-shaped conductive patterns X1˜X4 and Y1˜Y4 are overlapped. Besides,the third conductive layer 150 depicted in FIG. 3C is not patterned. Inother words, the third conductive layer 150 is a single electrodeinstead of multiple electrodes. A plurality of linear electrodes 170 isdisposed around the third conductive layer 150, and a material of thelinear electrodes 170 is, for example, aluminum, silver, copper, gold,or other metals. Practically, the second conductive layer 140, thespacers 160, the third conductive layer 150, and the linear electrodes170 interposed between the second substrate 120 and the first substrate110 together form a five-wire resistive touch panel, for example. On theother hand, boundaries of each of the bar-shaped conductive patternsX1˜X4 and Y1˜Y4 can partially or entirely have a non-straight linearshape, such as a subtle wave shape or a subtle saw tooth shape.

In particular, referring to FIGS. 3A through 3C, as the conductivematerial including a user's hand without wearing any glove or a stylusmade of the conductive material approaches or directly contacts a pointA on the first conductive 130, the variation of the induced capacitanceis generated between the bar-shaped conductive patterns X3 and Y3. Thevariation of the induced capacitance can be converted to thecorresponding coordinate signal by means of a converter in the controlcircuit. Here, the user's hand or the conductive stylus may not berequired to be in direct contact with the first conductive layer 130. Itis likely for the user's hand or the conductive stylus to merelyapproach the point A, such that the corresponding induced capacitancebetween the first conductive layer 130 and the second conductive layer140 can be generated. Hence, the touch panel 100 can be driven eventhough the touch panel is not directly touched. Moreover, given that thepoint A of the touch panel 100 is contacted by a non-conductivematerial, the capacitance between the bar-shaped conductive patterns X3and Y3 is not varied, and thus the medium used by the user for drivingthe touch panel 100 must actually contact the point A of the touch panel100. In an alternative, the point A of the touch panel 100 must bepressed for driving the touch panel 100. As such, the bar-shapedconductive pattern Y3 and the third conductive layer 150 can beelectrically conducted at the point A, such that the bar-shapedconductive pattern Y3 is able to detect the voltage of the thirdconductive layer 150 corresponding to the point A. Thereby, theconverter can generate the corresponding coordinate signal based on thedetecting voltage.

In general, IT products using the touch panel 100 can perform variousfunctions by means of the coordinate signal converted based on thevoltage variation of the second conductive layer 140 or based on thevariation of the induced capacitance between the first conductive layer130 and the second conductive layer 140. That is to say, the touch panel100 can be operated by the user's hand, the stylus, or other media, suchthat touch panel 100 can be more user-friendly. Besides, the inducedcapacitance at different corresponding positions between the firstconductive layer 130 and the second conductive layer 140 can bedetected. As a result, the touch panel 100 is equipped with themulti-touch function.

To sum up, the touch panel of the embodiment has both the resistivetouch panel structure and the capacitive touch panel structure.Therefore, the touch panel of the embodiment is characterized byadvantages of both the resistive touch panel and the capacitive touchpanel. The touch panel of the present invention can output thecorresponding coordinate signal when the touch panel is approached orcontacted by user's fingers, the stylus, or other tools. Thereby, thetouch panel can be operated in a user-friendly manner. Moreover, thetouch panel of the embodiment is able to sense the capacitance variationat various points simultaneously; therefore, the touch panel is capableof multi-touch function.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A touch panel, comprising: a first substrate having an upper surfaceand a bottom surface opposite to the upper surface; a second substrateparallel to the first substrate; a first conductive layer disposed onthe upper surface of the first substrate; a second conductive layerdisposed on the bottom surface of the first substrate; a thirdconductive layer disposed on the second substrate and interposed betweenthe second substrate and the second conductive layer; and a plurality ofspacers interposed between the second conductive layer and the thirdconductive layer.
 2. The touch panel as claimed in claim 1, furthercomprising a plurality of linear electrodes disposed on the secondsubstrate and positioned around the third conductive layer, wherein thethird conductive layer is a single electrode.
 3. The touch panel asclaimed in claim 2, wherein a material of the linear electrodescomprises metals.
 4. The touch panel as claimed in claim 2, wherein amaterial of the linear electrodes comprises gold, silver, copper,aluminum, or a combination thereof.
 5. The touch panel as claimed inclaim 2, wherein the second conductive layer, the spacers, the thirdconductive layer, and the linear electrodes interposed between thesecond substrate and the first substrate together form a five-wireresistive touch panel.
 6. The touch panel as claimed in claim 1, whereinthe first substrate is a flexible substrate and the second substrate isa flexible substrate or a rigid substrate.
 7. The touch panel as claimedin claim 1, wherein the first conductive layer comprises a plurality ofbar-shaped conductive patterns substantially arranged in parallel. 8.The touch panel as claimed in claim 7, wherein the second conductivelayer comprises a plurality of bar-shaped conductive patternssubstantially arranged in parallel.
 9. The touch panel as claimed inclaim 8, wherein a long axis of the bar-shaped conductive patterns ofthe second conductive layer is substantially perpendicular to a longaxis of the bar-shaped conductive patterns of the first conductivelayer.
 10. The touch panel as claimed in claim 1, wherein a material ofthe first conductive layer, the second conductive layer, and the thirdconductive layer comprises an transparent oxide conductive material. 11.The touch panel as claimed in claim 10, wherein the oxide conductivematerial comprises indium tin oxide (ITO) or indium zinc oxide (IZO).12. The touch panel as claimed in claim 1, further comprising a planarlayer covering the first conductive layer.
 13. The touch panel asclaimed in claim 1, wherein the first substrate, the second substrate,the first conductive layer, the second conductive layer, and the thirdconductive layer are made of transparent materials.
 14. A driving methodof a touch panel, the touch panel comprising: a first substrate, havingan upper surface and a bottom surface opposite to the upper surface; asecond substrate, parallel to the first substrate; a first conductivelayer, disposed on the upper surface of the first substrate; a secondconductive layer, disposed on the bottom surface of the first substrate;a third conductive layer, disposed on the second substrate andinterposed between the second substrate and the second conductive layer;and a plurality of spacers, interposed between the second conductivelayer and the third conductive layer, wherein the driving methodcomprises outputting a coordinate signal based on a voltage variation ofthe second conductive layer or based on a variation of an inducedcapacitance between the first conductive layer and the second conductivelayer.
 15. The driving method of the touch panel as claimed in claim 14,further comprising inputting a reference signal to the third conductivelayer.
 16. The driving method of the touch panel as claimed in claim 14,further comprising detecting the variation of the induced capacitancebetween the first conductive layer and the second conductive layer. 17.The driving method of the touch panel as claimed in claim 14, furthercomprising detecting the voltage variation of the second conductivelayer.